CHEM 2310 Midterm: 59-235 midterm 1 review.pdf

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oliveplatypus874

16 May 2013

School

University of Windsor

Department

Chemistry and Biochemistry

Course

CHEM 2310

Professor

Green

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Document Summary

N = 1: if the number of electrons falls on one of the intervals (2, 6, 10 ) then it is said to be aromatic. Aromatic: mo reason for stability in aromatic compounds paired electrons in bonding orbitals. Anti aromatic have unpaired electrons unstable: 4n -electrons (n = 0,1,2, these are classified as antiaromatic. If the number of -electrons does not fit into either of these categories it is known as. Only lone pairs that are in the same plane are counted in the -electron system . Electrons in p-orbitals orthogonal to the system do not contribute to the -electron count. Benzene due to resonance between bonds, no bond of benzene is strictly single or double ( ) but rather a midway point between them. ) in terms of length: single 1. 32a, double 1. 53a, benzene 1. 398a (all, all c"s are sp2 hybridized entire molecule is flat, ortho (beside, meta (one removed, para (across from)

Related Questions

1. Of Huckel's requirements for aromaticity, only this one is NOT required in the case of some compounds to be considered aromatic? 8. Which sequence of reagents would produce b) The system must be monocyclic. c) There must be (4n + 2) Ï electrons. d) The Huckel number of electrons must be completely 2. Zn(Hg), conc. HC delocalized. 2. 4-amino-2-chlorobenzaldehyde is NOz H2N NO2 3. Which of the following compounds are aromatic? Hint: 9. Refer to the following list of possible answers: So ) halogen h) RC-O D diazonium ion a. What group weakly activates benzene to b. What group slightly deactivates benzene to SeAr because a) I and II only c)I, II and â ¢ b) II and III only d) I and IlI only SAr by a +I e-donor inductive effect? of its-I withdrawal inductive effect, but is an ortho-/para- director because of its +R resonance e-donor 4. Which one of the following compounds is anti-aromatie? c. What group inhibits Friedel-Crafts alkylation and acylation d. What species is the electrophile e. What species is formed when but strongly activates a halo benzene to S&Ar because of its strong -R e-withdrawal resonance effect? In which case is the indicated unshared pair of electrons Nora contributor to the Ï aromatic system? 5. in Friedel-Crafts acylation? aniline reacts with NaNO HCVS? 10. Arrange these benzene compounds in order of decreasing (fastest to slowest) SeAr reactivity: . Cyclopentadiene is unusually acidic for a hydrocarbon a) The carbon atoms are all sp hybridized. b) Cyclopentadiene is aromatic. c) Removal of a proton from cyclopentadiene yields an a) III > IV > 11 > 1 c) IV I> III d) IV > â ¡ > I> aromatic anion. d) Removal of a hydride ion from cyclopentadiene What might be predicted to happen when the following substance undergoes Friedel-Crafts acylation? produces an aromatic cation. 11. Recalling that benzene has a resonance energy of 152 k mol and naphthalene has a resonance energy of 255 k mol', predict the two positions which would be occupied by bromine when phenanthrene (below) undergoes addition of Brã (circle two numbers). a) Substitution occurs in ring A, o- to the methylene gro b) Substitution occurs in ring A, o-to the nitro group. c) Substitution occurs in ring A, m- to the methylene g d) Substitution occurs in ring B, o-/p- to the methylene e) Substitution occurs in ring B, m. to the methylene 10 9

CHEM 2310 Midterm: 59-235 midterm 1 review.pdf

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